Cu-Induced Redox Stabilization of Zn in Electrodeposited ϵ -CuZn 4 during CO 2 Electroreduction

The electrochemical reduction of CO 2 (CO2RR) to carbon monoxide (CO) represents a promising approach for converting a readily available carbon feedstock into valuable fuels and chemicals. While Zn is a low-cost, Earth-abundant CO2RR catalyst with high CO selectivity, it has sluggish oxide reduction kinetics and poor activity at low overpotentials. In this work, we explored the intermetallic alloy ϵ -CuZn 4 as a Zn-rich model system to investigate how Cu incorporation alters Zn’s surface chemistry and electrochemical behavior. Both Zn and ϵ -CuZn 4 films were synthesized via direct electrochemical deposition onto gas diffusion electrodes and characterized under conditions relevant to gas-fed CO 2 electrolysis. Electrochemical measurements reveal that Cu incorporation enhances catalytic activity and selectivity while significantly improving stability at low overpotentials. In situ X-ray absorption spectroscopy shows that Cu promotes rapid oxide reduction, circumventing Zn’s sluggish reduction kinetics and limited stability at low overpotentials. Complementary to X-ray absorption fine structure, density functional theory and Bethe-Salpeter equation simulations reveal that Cu incorporation shifts the Zn d-band center and delocalizes Zn d-states, altering adsorption energetics in a way that enhances CO 2 -to-CO conversion.